Electromechanical flywheel containment system

ABSTRACT

An electromechanical flywheel machine includes a multi-wall containment system used in connection with a motor-generator for exchanging energy with a flywheel mass.

PRIORITY CLAIM

This application claims the benefit of U.S. Prov. Pat. App. No.61/582,332 filed Dec. 31, 2011 and entitled ELECTROMECHANICAL FLYWHEELCONTAINMENT SYSTEM.

Known flywheels store kinetic energy, that is, the energy of motion.When called upon to release this energy, the flywheel slows as kineticenergy is depleted. Flywheels driving and driven by electric machinesare also known. For decades, such electromechanical machines have beenbuilt and have achieved varying degrees of operational success.Widespread application has, however, eluded flywheel manufacturers aseven the most advanced commercial machines suffer from significantoperational limitations while exceeding the cost of better performingalternatives. Despite persistent efforts by a small flywheelmanufacturing industry, modern electromechanical flywheels have foundonly narrow applications in a few niche markets and presently make nosignificant contribution to the developed world's energy supply.

BACKGROUND OF THE INVENTION

Known flywheels store kinetic energy, that is, the energy of motion.When called upon to release this energy, the flywheel slows as kineticenergy is depleted. Flywheels driving and driven by electric machinesare also know. For decades, such electromechanical machines have beenbuilt and have achieved varying degrees of operational success.Widespread application has, however, eluded flywheel manufacturers aseven the most advanced commercial machines suffer from significantoperational limitations while exceeding the cost of better performingalternatives. Despite persistent efforts by a small flywheelmanufacturing industry, modern electromechanical flywheels have foundonly narrow applications in a few niche markets and presently make nosignificant contribution to the developed world's energy supply.

Field of Invention

This invention relates to the electromechanical arts. In particular,evacuation, safety, heat transfer, and support functions of anelectromechanical flywheel are enabled, at least in part, by amulti-wall containment system.

Discussion of the Related Art

Electromechanical flywheels include machines operating under atmosphericconditions and machines operating under evacuated conditions. Whilemachines operating in evacuated environments have benefitted from highspeed operation, they have also been limited by available techniques tomanage magnetic part temperatures and safety containment.

SUMMARY OF THE INVENTION

The present invention provides an electromechanical flywheel having arotor encircling a stationary stator and stator windings including afield winding encircling an axis of stator rotation.

In an embodiment, an electromechanical flywheel comprises a coreassembly including a motor-generator stator; a motor generator rotorsurrounding the stator; the stator defining an axis of rotation, havinga field coil that encircles the axis of rotation, and having an armaturecoil that does not encircle the axis of rotation; a flywheel massencircles the rotor and is coupled to the rotor for rotation with therotor; and, an evacuable housing that encloses the flywheel mass. Therotor is supported by first and second spaced apart suspensionassemblies; the first suspension assembly includes a firstelectromagnetic bearing for applying centering and levitating forces tothe rotor; and, the second suspension assembly includes a secondelectromagnetic bearing for applying centering forces to the rotor.

In an embodiment, an electromechanical flywheel containment systemcomprises: inner and outer enclosures defining respective inner andouter walls; a projectile shield between the walls of the inner andouter enclosures; an energy exchange block including a core assemblyincluding a motor-generator stator and a stator support and a spinningassembly including a motor-generator rotor, a flywheel mass and a hub;the motor-generator rotor surrounding the motor-generator stator; theinner enclosure enveloping the energy exchange block; the outerenclosure enveloping the inner enclosure; a first annular flow passagefor transporting a fluid coolant, the first annular flow passage outerdiameter bounded by a wall of the outer enclosure; and, wherein acontainment system fluid circuit for transporting coolant includes thefirst annular flow passage and a stator support flow passage.

In an embodiment, the electromechanical flywheel containment systemabove further comprises: the inner and outer walls of the inner andouter enclosures concentrically arranged; the projectile shieldencircling the inner wall; a shroud encircling the projectile shield;the shroud encircled by the outer wall of the outer enclosure; the firstannular flow passage inner diameter bounded by the shroud; a secondannular flow passage bounded by the shroud and the projectile shield;and, wherein the containment system fluid circuit for transportingcoolant includes the second annular flow passage.

In yet another embodiment, an electromechanical flywheel containmentsystem comprises: inner and outer enclosures defining respective innerand outer walls: a projectile shield between the inner and outer walls;an annular flow passage for transporting a fluid coolant; the annularflow passage inner diameter bounded by the projectile shield; amotor-generator stator hanging from the inner enclosure; a rotatingassembly including a motor-generator rotor, defining an axis ofrotation, and encircling a motor-generator stator and defining an axisof rotation; a flywheel mass surrounding and coupled to the rotor; and,wherein a field winding of the stator encircles the axis of rotation andan armature winding of the stator does not encircle the axis ofrotation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingfigures. These figures, incorporated herein and forming part of thespecification, illustrate the present invention and, together with thedescription, further serve to explain the principles of the inventionand to enable a person skilled in the relevant art to make and use theinvention.

FIG. 1 shows a block diagram of an electromechanical flywheel machine inaccordance with the present invention.

FIG. 2 shows selected functions and equipment of the electromechanicalflywheel machine of FIG. 1.

FIG. 3 shows a first embodiment of the electromechanical flywheelmachine of FIG. 1.

FIG. 4 shows a second embodiment of the electromechanical flywheelmachine of FIG. 1.

FIG. 5A shows rotor poles of an electromechanical flywheel machine ofFIG. 1.

FIG. 5B shows rotor poles and a stator of an electromechanical flywheelmachine of FIG. 1.

FIG. 6 shows a lower bearing assembly and some related parts of anelectromechanical flywheel machine of FIG. 1.

FIG. 7 shows an upper bearing assembly and some related parts of anelectromechanical flywheel machine of FIG. 1.

FIG. 8 shows a third embodiment of the electromechanical flywheelmachine of FIG. 1.

FIGS. 9A-C show containment systems of the electromechanical flywheelmachine of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The disclosure provided in the following pages describes examples ofsome embodiments of the invention. The designs, figures, anddescriptions are non-limiting examples of certain embodiments of theinvention. For example, other embodiments of the disclosed device may ormay not include the features described herein. Moreover, disclosedadvantages and benefits may apply to only certain embodiments of theinvention and should not be used to limit the disclosed inventions.

FIG. 1 shows an electromechanical flywheel machine 100. Electricalinterconnections 104 electrically couple an energy exchange block 102,power electronics and controls 106, and an electric power network 108.

As used herein, unless otherwise stated, the term coupled refers to adirect or indirect connection such as A connected directly to B and Cconnected indirectly to E via D.

The energy exchange block 102 includes a spinning assembly 110 and acore assembly 112. A containment system 101 provides one or morecontainment features discussed below. The spinning assembly includes amotor-generator rotor 114, a flywheel mass 116, and a hub 118. The coreassembly includes a motor-generator stator 120 and a motor-generatorstator support 122. In various embodiments, the spinning assembly is, asshown here, shaft-less.

Electrical interconnections 104 include any of electrical conductorconnections, electrical interface devices, electrical transducers, andthe like. Power electronics and controls 106 include any of siliconand/or semiconductor devices, analog and digital processors, and relatedinterfaces including human interfaces. The electric power network 108is 1) a source of electric power to the energy exchange block 102 insome embodiments, 2) a user of electric power from the energy exchangeblock in some embodiments, and 3) both a source and a user of electricpower to and from the energy exchange block in some embodiments.

FIG. 2 shows selected electromechanical flywheel machine functions andequipment 200. Energy storage 202 is central to flywheel operation. Inelectromechanical flywheels, energy storage and energy conversion 204provide a means for converting kinetic energy to electrical power and/orconverting electrical power to kinetic energy. Energy transfer 206provides for electric power transfers between energy conversionequipment 220, 216 and an electric power network 108. In variousembodiments, an electrical switch such as a circuit breaker 230 providesfor connecting and disconnecting conductors enabling power transfer. Invarious embodiments, other electromechanical flywheel machine functionsinclude any of several auxiliary support functions 208 described below.

Energy storage 202 utilizes the spinning assembly 110. In variousembodiments, a suspension system 210 supports the spinning assembly.Suspension equipment includes bearings or their equivalents 212 and insome embodiments a passive shutdown system 215 supports the spinningassembly in selected operating regimes such as shutdown.

Energy conversion 204 utilizes a means for converting kinetic energyinto electrical power such as a generator or a motor-generator. Amotor-generator 220 is shown. The motor-generator includes the rotor 114and a stator 120 and provides a means for rotatably driving the spinningassembly 110 and for being rotatably driven by the spinning assembly. Invarious embodiments, power electronics 216 enable manipulation ofelectrical waveforms emanating from the motor-generator and/or theelectric power network 108. For example, in various embodiments, powerelectronics provide for frequency conversion in an AC to AC converterhaving an intermediate DC bus and power electronics provide for variablespeed drive functions such as accelerating the flywheel rotor.

In various embodiments, auxiliary support functions 208 are carried outby auxiliary support equipment described more fully below. Auxiliarysupport functions include housing 240, safety 242, vacuum 244, cooling248, and man-machine interface 246.

A control function 205 provides for one or more of monitoring,assessment, command, and control of other electromechanical flywheelfunctions. In particular, the control function enables electromechanicalflywheel operation via supervision and/or control of one or more of theenergy storage 202, energy conversion 204, energy transfer 206, andauxiliary support 208 functions.

FIG. 3 shows a first electromechanical flywheel portion 300. An energyexchange block 302 is enclosed by an inner housing 328 which is in turnenclosed by an optional outer housing 338.

The energy exchange block 302 includes a spinning assembly 310 and acore assembly 312. Included in the spinning assembly is amotor-generator rotor 314, a flywheel mass encircling and coupled to therotor 316, a hub 318 coupled to the flywheel mass, and a movingsuspension element 344. In some embodiments, a sleeve such as anon-magnetic sleeve is interposed between the rotor and the flywheelmass for, inter alfa, backing the rotor and providing support to therotor. The rotor, flywheel mass, hub, and moving suspension element arefor rotation in synchrony about an axis x-x and in various embodimentsthe hub is attached to one or both of the rotor 350 and the flywheelmass 352. Opposite the moving suspension element is a stationarysuspension element 346 supported via a first wall of the inner housing332. Included in the core assembly 312 are a stator 320 and a statorsupport 322. In some embodiments, the stator support is coupled to awall of the inner housing such as a second wall of the inner housing334.

Encircling the motor-generator stator 320 is the motor-generator rotor314. In various embodiments, the rotor 314 includes magnetic 354 andnonmagnetic 356 portions and, in some embodiments, the nonmagneticportion is or includes blocking or matrix material supporting themagnetic portions. In an embodiment, the magnetic rotor portions arelaminated structures.

In various embodiments, the stator 320 includes a magnetic structurewith one or more interengaged coils having electrically conductivewindings capable of carrying variable currents and thereby varying themagnetic flux of the magnetic structure. In some embodiments, a firststator coil 364 encircles an imaginary y-y axis that is aboutperpendicular to the x-x axis. And, in some embodiments, a second statorcoil 368 encircles the x-x axis. In an embodiment, a plurality of firststator coils encircle respective imaginary y-y axes and one or moresecond stator coils encircle the x-x axis, the first stator coils beingarmature coils and the second stator coils being field coils.

And, in an embodiment, the motor-generator 360 is a homopolar devicewith the illustrated inside-out arrangement (rotor encircles stator)wherein a) a rotatable rotor similar to rotor 314 includes coil-less,laminated magnetic structures, b) wherein a stationary central statorsimilar to stator 320 includes laminated magnetic structures with coilsfor creating a magnetic flux in the magnetic structures and c) the rotorencircles the stator.

FIG. 4 shows a second electromechanical flywheel portion 400. An energyexchange block 402 is enclosed by an inner housing 428 which isenclosed, or partially enclosed, in some embodiments, by an outerhousing (not shown).

The energy exchange block 402 includes a spinning assembly 410 and acore assembly 412. Included in the spinning assembly are amotor-generator rotor 414, a flywheel mass encircling and coupled to therotor 416, a hub coupled to the flywheel mass 418, a support pin forsupporting the hub 496, and a moving suspension assembly for supportingthe hub 492. Some embodiments include a sleeve such as a non-magneticsleeve between the rotor and the flywheel mass.

In various embodiments, the flywheel mass 416 includes layers ofdifferent materials such as fiberglass in one or more types or gradesand carbon fiber in one or more types or grades. U.S. Pat. No. 6,175,172entitled HUB AND CYLINDER DESIGN FOR FLYWHEEL SYSTEM FOR MOBILE ENERGYSTORAGE is incorporated by reference herein in its entirety and for allpurposes including flywheel mass construction techniques and materials.

As shown, the flywheel mass includes three layers with a first layer 417adjacent to the rotor, an intermediate layer 419, and an outer layer421. In an embodiment, the intermediate and outer layers include carbonfiber materials and the inner layer includes fiberglass. In anotherembodiment, all three layers are substantially made from carbon fibermaterials. In various embodiments, one or more layers are pre-stressedsuch as by winding fibers under tension to form substantiallycylindrical shell(s) with inherent compressive stress.

The support pin, moving suspension assembly and hub are concentricallyarranged and are for rotation in synchrony about an axis x-x. As seen,the support pin 496 is located in a gap 491 between upper and lowerbearing carriers 490, 494. Extending from the stator support 422 is anupper bearing carrier and supported from a first wall of the housing 432is a lower bearing carrier. In an embodiment, elongation of the upperbearing carrier along the x-x axis 493 serves to rotatably restrain thesupport pin between the upper and lower bearing carriers. In this sense,the upper and lower bearing carriers provide a means to “capture” thespinning assembly 410 via the support pin and are useful for functionsincluding passive shutdown. In various embodiments, the lower bearingcarrier and the moving suspension assembly incorporate a firstelectromagnetic bearing.

A second electromagnetic bearing 451 is spaced apart from the upper andlower bearing carriers 490, 494. The second electromagnetic bearingincludes a fixed bearing stator 454 supported by the stator support 422and electrical windings 452 for magnetizing the stator and ageometrically opposing rotor 456 coupled to the rotor. As shown, themating faces of the electromagnet 498, 499 are parallel to the x-x axissuch that electromagnetic bearing forces are perpendicular to the x-xaxis. In other embodiments, angled electromagnetic bearing faces such asthose described above provide electromagnetic bearing force componentsalong an axis parallel to the x-x axis and along an axis perpendicularto the x-x axis.

Included in the core assembly 412 is a stator 420 and a stator support422 coupled to a second wall of the inner housing 434. Encircling themotor-generator stator is the motor-generator rotor 414. In variousembodiments, the rotor includes magnetic and nonmagnetic portions (e.g.,see 354, 356 of FIG. 3) and, in some embodiments, the nonmagneticportion is or includes blocking or matrix material supporting themagnetic portions. In an embodiment, the magnetic rotor portions arelaminated structures.

In various embodiments, the stator 420 includes a magnetic structurewith one or more interengaged coils having electrically conductivewindings capable of carrying variable currents and thereby varying themagnetic flux of the magnetic structure.

A typical homopolar stator includes at least two peripheral rims and onesmaller intermediate rim. The rims include a magnetic material such asiron and in various embodiments the rims are laminated structures witheach laminate having a substantially annular shape.

As shown, the stator 420 includes three large diameter rims 464, 466,470 and two smaller diameter rims 484, 488 such that substantiallyannular or somewhat doughnut shaped pockets 481 are formed between thelarge diameter and the small diameter rims. It is in these pockets thatcoils encircling the rotational axis x-x are placed to form fieldwindings 482, 486. In addition to the field coil(s), the stator alsoincludes armature coils.

Armature coils 450 are interengaged with slots 483 in the periphery ofthe large rims 464, 466, 470 such that each armature coil will encirclean imaginary axis y-y that is substantially perpendicular to the axis ofrotation x-x (see FIG. 3).

For each stator rim, there is a plurality of mating rotor poles. As canbe seen, the peripheral stator rims 464, 470 have axially spaced (x-x)mating rotor pole 462, 468 (shown in solid lines) and the central statorrim 466 has axially adjacent mating rotor poles 463, 469 (shown inbroken lines). Rotor poles for adjacent rims (e.g., 462, 463) are notonly axially spaced (x-x), but they are also radially spaced such that arotor pole for one rim is radially spaced by 90 electrical degrees fromthe closest rotor pole mating with an adjacent rim.

In various embodiments, internal vacuum pumps such as molecular dragpumps provide for moving molecules away from the flywheel mass 416 andespecially away from the flywheel mass periphery where the highestspeeds are achieved. U.S. Pat. No. 5,462,402 FLYWHEEL WITH MOLECULARPUMP is incorporated by reference herein in its entirety and for allpurposes including its discussion of molecular drag pumps and theirincorporation into flywheel systems.

In an embodiment, a first vacuum pump is formed by a stationarylabyrinth like ring 458 supported from the housing wall 434 which isclosely spaced with respect to a vacuum pump surface of the flywheelmass 459. In various embodiments grooves in the labyrinth ring providefor a pumping action in concert with the moving flywheel surface. Insome embodiments, the groove is a spiral having a cross-sectional areathat generally decreases along a forward flow path. And, in someembodiments, a second vacuum pump is formed by a labyrinth similar tothe one described above and fixed to peripheral stator parts (such asthe large diameter stator rings 454, 464, 466, 470, not shown forclarity) or fixed to geometrically opposed rotor poles (456, 462, 463,469, 468).

In an embodiment, a supply region and an exhaust region are includedwithin the evacuable housing. The supply region has a boundary definedat least in part by portions of a housing 428, a hub exterior surface417, and a flywheel mass periphery 413. The exhaust region has aboundary defined at least in part by portions of the vacuum barrierhousing and the core assembly 412. A first drag pump is interposedbetween a flywheel mass surface 459 and the vacuum barrier housing wall434 and a second drag pump is interposed between at least one statorring 466 and the rotor 414.

FIG. 5A shows a radially staggered arrangement of rotor poles inadjacent pole planes for a 2+2 pole single stage homopolar machine 500A.Referring to rotor cross section 502 and rotor 514, a first pole 462 islocated in a first pole plane Y1 and an opposed pole 463 in located inthe same plane. In a similarly clocked adjacent pole plane Y2, anadjacent plane pole 465 is between the Y1 plane poles. Not shown in thiscross section is the second pole in the Y2 plane 464.

The plane views 504, 506 of the pole planes Y1, Y2 show the poles ineach pole plane 462, 463 and 464, 465 are separated by a 90° geometricangle. In this four pole embodiment, the poles are similarly separatedby 90 electrical degrees.

In various embodiments, a magnetic path extends between adjacentstaggered poles. For example, as shown in the pole assemblies 508, 510,magnetic path parts 466, 468 extend between pole pairs 462, 463 and 463,464. As shown here, two continuous magnetic paths are formed in a fourpole machine rotor by magnetic path parts 462-466-465 and 463-468-464.In some embodiments, each magnetic path part assembly 462-466-465 and463-468-464 is “Z” shaped with the central members 466, 468 meetingadjoining members 462, 465 and 465, 464 at substantially right angles.Among other things, this structure preserves the capacity of themagnetic path.

FIG. 5B shows a rotor and a stator for a three stage machine, each stagehaving four poles 500B. Here, a view of rotor magnetic path partassemblies 560 is shown as if the normally cylindrical rotor structureis “unrolled” such that a planar surface is presented. The magnetic pathpart assemblies 520, 522, 523, 521 are arranged to create a lattice 569with spaces between the parts 519, the spaces being filled, in variousembodiments, with non-magnetic material(s).

The lattice 569 is constructed such that a plurality of stages A, B, Cis formed, each stage having four poles. For example, stage A has aNorth plane with a first full pole 557 and a second pole consisting oftwo half-poles 553, 555. Stage A also has a South plane with two fullpoles 559, 560. The North and South planes of Stage A therefore have atotal of four complete poles.

Each stage includes four magnetic path part assemblies or rotor latticeparts. For example, Stage A includes magnetic path part assemblies 520,522, 520, and 522; Stage B includes magnetic path part assemblies 523,521, 523, and 521; and Stage C, like Stage A, includes magnetic pathpart assemblies 520, 522, 520 and 522. Notably, in various embodiments,the path part assemblies differ only in their orientation; for example,assembly 520 differs from assembly 522 by an 180° rotation about an axisparallel to the x-x axis while assembly 520 differs from assembly 523 byan 180° rotation about an axis perpendicular to the x-x axis. Assembly522 differs from assembly 521 by an 180° rotation about an axisperpendicular to the x-x axis.

Also shown is a cross sectional view of a stator 562. As seen, thestator has large 534, 536, 538, 540 and small 544, 546, 548 diameterrims centered on an x-x axis. First and second large diameterintermediate rims 536, 538 are interposed between large diameterperipheral rims 534, 540. One small diameter rim is interposed betweeneach pair of large diameter rims such that the rims are stacked in anorder 534, 544, 536, 546, 538, 548, and 540. The rims are supported by acoupled stator support 532 that is supported via a wall 530.

A plurality of armature windings, for example 571, 572 interengage aplurality of the large diameter rim peripheries, for example 574 viaslots or a similar feature. Field windings 535, 537, 539 encircle thestator axis of rotation x-x with one field winding encircling each ofthe small diameter rims such that each field winding is between a pairof large diameter rims.

As can be seen, the lattice structure of the rotor 569 is arranged suchthat the first rim of the stator 534 corresponds to the North poles ofstage A; the third rim of the stator 536 corresponds to the South polesof stage A and the South poles of stage B; the fifth rim of the statorcorresponds to the North poles of stage B and the North poles of stageC; and, the seventh rim of the stator corresponds to the South poles ofstage C.

In various embodiments, bearings are used to support the spinningassembly and the included flywheel mass 116, 316, 416. Any combinationof the bearings described herein that is sufficient to support thespinning assembly may be used.

FIG. 6 shows a lower bearing carrier and some related parts 600. Asshown in the upper half of the drawing, there is a hub 618 for couplingto a flywheel mass, a support pin 696 for supporting the hub 618, amoving suspension assembly for supporting the hub 692, and a lowerbearing carrier 694. The hub, support pin, and moving suspensionassembly are fixedly coupled together (shown in FIG. 6 in explodeddiagram format for clarity).

In various embodiments, the moving suspension assembly 692 includes amoving suspension assembly electromagnetic bearing rotor 602. In someembodiments, the bearing rotor is a laminated structure (as shown). Insome embodiments, the bearing has a moving suspension assemblyelectromagnetic bearing face 603 oriented at an angle θ1=0° where theangle is defined by the face and an axis x1-x1 parallel to the x-x axis.And, in some embodiments, the bearing has a face 603 oriented at anangle 0<θ1<90° (“angled face”) (as shown) providing electromagneticbearing force components parallel to the x-x axis and parallel to anaxis perpendicular to the x-x axis.

In various embodiments, the moving suspension assembly 692 includes amoving suspension assembly permanent magnet 604 and in some embodimentsthe permanent magnet is in addition to the electromagnetic bearing rotor602. And, in some embodiments, a moving suspension assembly magnetholder 606 provides a holder for either or both of the moving suspensionassembly electromagnetic bearing rotor and the moving suspensionassembly permanent magnet.

When the moving suspension assembly includes an electromagnetic bearingrotor 602, the lower bearing carrier 694 includes a corresponding lowerbearing carrier electromagnetic bearing stator 614 and a lower bearingcarrier stator electrical coil 616 for magnetizing the stator. Thestator is supported by a lower bearing carrier frame 612 which is inturn supported by a housing wall 632.

In some embodiments, the bearing stator is a laminated structure (asshown). In some embodiments, the bearing has a lower bearing carrierelectromagnetic bearing face 615 oriented at an angle θ2=0° where theangle is defined by the face and an axis x2-x2 parallel to the x-x axis.And, in some embodiments, the bearing has a face 615 oriented at anangle 0<θ2<90° (“angled face”) (as shown) providing electromagneticbearing magnetic force components parallel to the x-x axis and parallelto an axis perpendicular to the x-x axis. As will be appreciated bypersons of ordinary skill in the art, the bearing faces 603, 615interoperate such that a straight rotor face is matched with a straightstator face while an angled rotor face is matched with an angled rotorface.

Where a moving suspension assembly permanent magnet is used 604, thelower bearing carrier includes a geometrically opposed permanent magnet620. In some embodiments, a lower bearing carrier permanent magnetholder 619 supported from the lower bearing carrier frame 612 andsupporting the permanent magnet.

In various embodiments, the lower bearing carrier 694 includes a lowerbearing carrier landing bearing such as an antifriction bearing 622. Asshown, the landing bearing is supported from the lower bearing carrierframe 612. In some embodiments, a damping material 624 provides aseating material for the landing bearing.

FIG. 7 shows an upper bearing carrier and some related parts 700. Asshown, the upper bearing carrier 790 includes a stationary plate 702 anda moving plate 704.

The stationary plate 702 includes a coil space 706 in the form of agroove is on a side of the stationary plate facing the moving plate 730.An electrical coil 722 for magnetizing a magnetic material surrounded bythe coil 707 is included.

The moving plate 704 includes a spring space 708 and a mechanicalbearing space 710. The spring space 708 is formed where a reduceddiameter section of the moving plate extends to the side of the platefacing the stationary plate 732 and a spring such as a coil spring 720occupies this space. The bearing space 710 is a central cavity in amoving plate surface 734 opposite the moving plate surface facing thestationary plate 732. As seen, operation of this electromagnetcompresses the spring and tends to draw the plates together.

In various embodiments, the upper bearing carrier 790 includes an upperbearing carrier landing bearing such as an antifriction bearing 716. Asshown, the landing bearing is positioned in the moving plate cavity 710.In some embodiments, a damping material 718 provides a seating materialfor the landing bearing.

As seen in FIGS. 6 and 7, the support pin 696 extends between the upperbearing carrier 790 and the lower bearing carrier 694. Further, each ofthe upper bearing carrier landing bearing 716, support pin 696, movingsuspension assembly 692, lower electromagnetic bearing stator 614, lowerbearing carrier permanent magnet 620, and lower bearing carrier landingbearing 622 is centered on the x-x axis such that when the moving plate704 moves toward the lower bearing carrier 793, the support pin upperand lower ends 728, 628 are engaged with respective upper and lowerlanding bearings 716, 622 and a central aperture of each landing bearing726, 626.

FIG. 8 shows another embodiment of an electromechanical flywheel 800. Aflywheel mass 831 surrounds and is coupled to a homopolarmotor-generator rotor including a metallic liner 830. As shown, therotor includes North rotor poles 824, 832. Not shown are the South rotorpoles; see stages A and B of FIG. 5B for a similar arrangement thatlocates the South rotor poles.

A stator support 811 is coupled to a motor-generator stator 828 and eachof field windings 826 and armature windings 820 are interengaged withthe stator in a manner similar to that described above.

Supporting the rotor 830 and flywheel mass 831 is a hub 846 that is inturn supported by a support pin 864 engaging and/or located betweenupper and lower bearing carriers 860, 862. See FIGS. 6 and 7 for detailsof similar bearing carriers. A first electromagnetic bearing 866 islocated in the lower bearing carrier. A second electromagnetic bearing870 is spaced apart from the first and second bearing carriers andincludes a bearing stator 818, a bearing rotor 818 and stator coils 814for magnetizing the stator.

An electromechanical flywheel housing includes an inner vacuum barrier812. In some embodiments, an outer housing 807 supports the vacuumbarrier. Suitable vacuum barrier materials include stainless steel andother materials known by skilled artisans to be suited to this purpose.

In various embodiments, the stator support 811 has a tubular structureand a coaxial tube 801 is located therein. As shown, the coaxial tubeenvelops a liquid coolant flow entering the stator support 802 and anannulus between the support structure inside diameter and the coaxialtube outside diameter 815 provides a flow path for coolant leaving thestator support 803. Coolant traveling through the annulus absorbs heatfrom the stator 828 and is in various embodiments cooled in a cooler(not shown) before it is pumped (not shown) back into the flow entry802.

Heat pipes 808 provide stator cooling in some embodiments. As shown,each of a plurality of heat pipes has a heat absorbing first end inclose proximity to the stator, such as in the stator armature windingslots (as shown) 872. The heat rejecting end of the heat pipe is inclose proximity to the vacuum barrier, such as in contact with vacuumbarrier (as shown) 874 or in other embodiments cooled by the abovementioned liquid coolant flow.

As can be seen from the descriptions above, electromechanical flywheel100 systems and structures, such as the cooling system 248 and thestator support 122, may have interrelated designs.

Containment systems 101 provide additional examples of interrelateddesigns. In various containment system embodiments, a plurality ofinterrelated structures provides one or more of structural support, avacuum barrier, a projectile shield, fluid coolant passages, and heattransfer paths.

FIG. 9A shows an exploded cross-sectional view of a multipurposecontainment system 900A. The multipurpose containment system includes aninner enclosure 906 for providing a vacuum barrier, an intermediateenclosure 904 for providing a projectile shield, and an outer enclosure902 for providing a fluid coolant passage. These and other features ofthe multiple enclosures are described in more detail below.

Inner enclosure 906 includes an inner cylindrical wall 936. An inner lid916 is operable to close one end of the cylinder via a cylinder flange946 and an inner floor 926 closes the cylinder's opposing end. As shownin this embodiment, a stator support 987 hangs from a central portion ofthe inner lid. The inner enclosure is made from a suitable vacuumsealing material such as metals, for example aluminum and/or stainlesssteel. Aluminum and stainless steel also promote a clean evacuatedenvironment as they resist oxidation and the formation of contaminatingparticulates. In various embodiments, a clean evacuated environmentpromotes operation of vacuum pumps including drag pumps and promotesmaintenance of a suitable vacuum pressure.

Intermediate enclosure 904 envelopes the inner enclosure 906. Theintermediate enclosure includes an inner cylindrical wall 934. Anintermediate lid 914 is operable to close one end of the cylinder suchthat the lid of the inner enclosure 916 is sealed between an end face ofthe intermediate cylinder 944 and the intermediate lid. An intermediatefloor 924 closes the cylinder's opposing end. The intermediate enclosureis made from a suitable projectile shielding material such as metals,for example steel and/or steel alloys. A suitable material thickness ischosen taking into consideration the material used and the energy thatmust be absorbed during a selected design failure scenario(s).

While a gap is shown (for clarity) between the inner and intermediateenclosures 906, 904, embodiments with interference fits and/or a heattransfer compound therebetween enable heat transfer from one wall to theother. For example, heat radiated from a stator (see e.g., FIG. 8, 828)is transferred to the wall of the inner enclosure 936 and, absent a gap,via conduction to the wall of the intermediate enclosure 934.

Outer enclosure 902 envelops the intermediate enclosure 904. The outerenclosure includes an outer cylindrical wall 932. An outer lid 912 isoperable to close one end of the cylinder via a cylinder flange 942 andan outer floor 922 closes the opposing end. The outer enclosure is madefrom a suitable coolant passage material such as metals, for examplesteel and/or steel alloys.

A flow divider shroud 908 includes a cylindrical shroud wall 938 fordividing the annulus between the intermediate wall 934 and the outerwall 932 into inner and outer annuli 951, 953. An end of the cylindricalshroud wall includes an inwardly directed sealing ring 948 for sealingbetween the cylindrical shroud wall and an adjacent structure such asthe intermediate cylindrical wall 934, the inner lid 916, and/or theintermediate lid 914. One or more (two shown) coolant fluid exitconduits 958 penetrate the sealing ring and provide a means forexchanging fluid with the inner annular space 951. The shroud is madefrom a suitable coolant passage material such as metals and plastics. Inan embodiment, the shroud is made from a plastic such as a high densitypolyethylene plastic or a polyvinyl chloride plastic.

FIG. 9B shows a simplified cross-section 900B of the containment systemof FIG. 9A. As seen, the inner wall 936 is encircled by the intermediatewall 934 and the intermediate wall is encircled by an outer wall 932.The outer wall encircles the shroud wall 938 and the shroud wallencircles the intermediate wall 934 such that the annulus between theintermediate and outer wall is divided into inner 951 and outer 953annuli.

FIG. 9C shows the containment system of FIG. 9A after its assembly 900C.For clarity, flywheel internals including the stator 120, rotor 114, andflywheel mass are not shown. See FIG. 8 for exemplary flywheelinternals.

During flywheel operation, heat is released within the inner enclosureflywheel space 981. In various embodiments, this heat is transferred toone or both of a fluid coolant (indicated by flow arrows) and to thesurroundings 983. As the fluid coolant moves through the flow passagesand elsewhere in the cooling system, heat is alternately absorbed by andrejected by the fluid coolant.

Coolant flow enters the containment system 960 via coolant entry conduit988 that is inserted in a stator support central cavity 991 defining astator support annular flow space 992. Flow from the entry conduit 962empties into the annular flow space 964 where it absorbs heattransported to the stator support wall 993. Flow from the stator supportannulus 966 is transported to a fluid plenum 968 between the outer lid912 and the intermediate lid 914. Flow leaving the plenum 970 istransported to the outer annulus 953. In various embodiments, thecoolant rejects heat to the surroundings 983 via heat transfer acrossthe outer enclosure wall 932. Flow 972 from the outer annulus 953 istransported to the inner annulus 974. In various embodiments, thecoolant absorbs heat via heat transfer across the intermediate and innerenclosure walls 934, 936. Flow 976 from the inner annulus 951 istransported to the fluid coolant exit conduit(s) 978.

In operation, a flywheel mass of the electromechanical flywheel isaccelerated by the motor-generator during flywheel charging. Duringcharging, energy is transferred to the motor-generator. Duringdischarge, the motor-generator converts the kinetic energy of theflywheel into electrical energy as the flywheel mass is decelerated.Power electronics provide for conversion of network electric power inorder to motor the motor-generator and the mechanically coupled flywheelmass. Power electronics also provide for conversion of motor-generatorgenerated electric power into a waveform suited for use by theelectrical network to which the electric power is transferred.

In operation, a containment system provides a projectile shield. Forexample, as shown in FIG. 9C, containment system 900C provides aprojectile shield 906 should a failure such as a flywheel failure occur.In various embodiments: a vacuum barrier is provided by an innerenclosure 902 which enables vacuum maintenance in the flywheel space981; a coolant flow space is provided by an outer enclosure 902; and,the coolant flow space is divided into inner and outer annular flowpassages 951, 953 by a flow divider shroud 908. Heat absorbed by coolantflowing in the stator support 987 and heat absorbed by coolant flowingin the inner annular flow passage is rejected via one or both of heattransfer through the outer enclosure wall 932 to the environment 983 andheat transferred from the fluid external to the containment system suchas via a fin-fan cooler (not shown).

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be apparent to those skilledin the art that various changes in the form and details can be madewithout departing from the spirit and scope of the invention. As such,the breadth and scope of the present invention should not be limited bythe above-described exemplary embodiments, but should be defined only inaccordance with the following claims and equivalents thereof.

What is claimed is:
 1. An electromechanical flywheel containment systemcomprising: inner and outer enclosures defining respective inner andouter walls; a projectile shield between the walls of the inner andouter enclosures; an energy exchange block including a core assemblyincluding a motor-generator stator and a stator support and a spinningassembly including a motor-generator rotor, a flywheel mass and a hub;the motor-generator rotor surrounding the motor-generator stator; theinner enclosure enveloping the energy exchange block; the outerenclosure enveloping the inner enclosure; a first annular flow passagefor transporting a fluid coolant, the first annular flow passage outerdiameter bounded by a wall of the outer enclosure; and, wherein acontainment system fluid circuit for transporting coolant includes thefirst annular flow passage and a stator support flow passage.
 2. Theelectromechanical flywheel containment system of claim 1 furthercomprising: the inner and outer walls of the inner and outer enclosuresconcentrically arranged; the projectile shield encircling the innerwall; a shroud encircling the projectile shield; the shroud encircled bythe outer wall of the outer enclosure; the first annular flow passageinner diameter bounded by the shroud; a second annular flow passagebounded by the shroud and the projectile shield; and, wherein thecontainment system fluid circuit for transporting coolant includes thesecond annular flow passage.
 3. An electromechanical flywheelcontainment system comprising: inner and outer enclosures definingrespective inner and outer walls: a projectile shield between the innerand outer walls; an annular flow passage for transporting a fluidcoolant; the annular flow passage inner diameter bounded by theprojectile shield; a motor-generator stator hanging from the innerenclosure; a rotating assembly including a motor-generator rotor,defining an axis of rotation, and encircling a motor-generator statorand defining an axis of rotation; a flywheel mass surrounding andcoupled to the rotor; and, wherein a field winding of the statorencircles the axis of rotation and an armature winding of the statordoes not encircle the axis of rotation.
 4. An electromechanical flywheelcontainment system comprising: inner and outer enclosures definingrespective inner and outer walls; the inner enclosure operable toprovide a vacuum barrier; a projectile shield between the walls of theinner and outer enclosures; an energy exchange block including a coreassembly including a motor-generator stator and a stator support and aspinning assembly including a motor-generator rotor, a flywheel mass anda hub; the motor-generator rotor surrounding the motor-generator stator;the inner enclosure enveloping the energy exchange block; the outerenclosure enveloping the inner enclosure; a first annular flow passagefor transporting a fluid coolant, the first annular flow passage outerdiameter bounded by a wall of the outer enclosure; and, wherein acontainment system fluid circuit for transporting coolant includes thefirst annular flow passage and a stator support flow passage.